run-command: support custom fd-set in async

This patch adds the possibility to supply a set of non-0 file
descriptors for async process communication instead of the
default-created pipe.

Additionally, we now support bi-directional communiction with the
async procedure, by giving the async function both read and write
file descriptors.

To retain compatiblity and similar "API feel" with start_command,
we require start_async callers to set .out = -1 to get a readable
file descriptor.  If either of .in or .out is 0, we supply no file
descriptor to the async process.

[sp: Note: Erik started this patch, and a huge bulk of it is
     his work.  All bugs were introduced later by Shawn.]

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/run-command.h b/run-command.h
index a29171adae..65ccb1c60f 100644
--- a/run-command.h
+++ b/run-command.h
@@ -64,17 +64,20 @@ int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const
  */
 struct async {
 	/*
-	 * proc writes to fd and closes it;
+	 * proc reads from in; closes it before return
+	 * proc writes to out; closes it before return
 	 * returns 0 on success, non-zero on failure
 	 */
-	int (*proc)(int fd, void *data);
+	int (*proc)(int in, int out, void *data);
 	void *data;
+	int in;		/* caller writes here and closes it */
 	int out;	/* caller reads from here and closes it */
 #ifndef WIN32
 	pid_t pid;
 #else
 	HANDLE tid;
-	int fd_for_proc;
+	int proc_in;
+	int proc_out;
 #endif
 };